Northrop Grumman B-21 Raider (LRS-B)

[rooster]

Neither the B-2 nor F-117 had pylons, so pylons seem unlikely for a stealth bomber.

As noted elsewhere there have been studies involving external drop tanks that when dropped the rcs is as if they were never even there. This is done through close able panels and doors. But as everyone *should* know external drop tanks don't offer the range per pound as internal fuel.

 

[rooster]

Those aren't in service and the B-1 isn't a low RCS platform.

The B-1B was designed for reduced observables. The ACM pylons were designed to minimize the impact on RCS. Today there is an effort underway to carry JASSM externally.

I read somewhere the AGM-129 was designed for supersonic external carriage. Presumably on the B-1B back in the day.

With what a bomber with a 600 mile range. Those external stores are draggy and it gets worse with velocity.

B1 was never low observable. They would have been better off spending money elsewhere than on those meaningless signature reductions. They would have been better off not messing with the intakes that significantly reduced its speed

 

[SteveO]

Maxing out the take off weight with external stores might make sense if the B-21 was self deploying with reload weapons for itself or other aircraft as trialled by USAF F-15E’s recently.

They could always study a float plane amphibious conversion like the SOCOM C-130 project too

Pretty sure the basic version is going to be more than adequate though!

 

[GeorgeA]

It makes sense to allow for external carriage for potential stand-off employment anyway, providing it doesn't compromise the standard mission. Just like the F-22 and F-35 can carry external loads.

This was confirmed by the USAF four-star, who was the commander of STRATCOM when the program was launched, on the Aerospace Advantage podcast. He wanted the LRS-B to have the ability to carry external ordnance for stand-off missions.

 

[The K2]

Lets call him "Tim".

Monty Pythons and the holy grail intensifies... KABOOM !!!

 

[NeilChapman]

You say that B-21 carrying external payload is "known." Then provide a source for this knowledge.

It was probably Tirpak bits of info at AFM, not AWST or Flight Int. I thought then that idea as absurd as you do now, so I remember it very well - also because it was probably only bit of RFP that leaked.
If you think that this is just my imagination, I'm OK with that.

I remember hearing a discussion re external hard points for B-21. I remember it bc it struck me at the time "why on a stealth bomber." I just went looking for it and cannot find the reference. The person stated they fought for or insisted on hard points. So ,,,there you go.

I see many reasons for Raider Beast mode.

1. As the future backbone of the force it will not always be required to be stealthy.

2. With air supremacy and at >60k feet there may be little risk.

3. Flying in w/drop tanks may provide the loiter time required.

4. Working your way in to an A2AD environment you may be loaded with larger, longer range standoff weapons.

5. And all the reasons I cannot think of today which may arise over the next 20 years.

 

[Josh_TN]

Those aren't in service and the B-1 isn't a low RCS platform.

The B-1B was designed for reduced observables. The ACM pylons were designed to minimize the impact on RCS. Today there is an effort underway to carry JASSM externally.

"Reduced" in this case is several orders of magnitude lower reduction than a B-2. An F-18E has a reduced RCS, though not to the point that anyone cares if you hang something off it. The B-1's signature reductions were more to make its ECM and low level penetration mode more effective, not attempt to obscure it from almost all emitters at most frequencies. A rather different approach. Also per a former Bone navigator, none of the RAM surfaces are maintained as such for many years. I don't see any reason anyone would put a mark on the coating or hard spot on the structure of a B-2 or B-21.

Nobody has EVER claimed the RCS reduction efforts implemented on the B-1B gave it B-2 levels of reduction. Basically it was enough that it made it more survivable than the Mach 2+ speed of the B-1A. That's about it.

My point is that those are two different levels of RCS reduction that encourage completely different tactics. Saying a B-21 will have external ordnance because a B-1 used to is like saying “if you liked the movie Twister, you’ll LOVE Gone With The Wind!”.

 

[NeilChapman]

How much of RCS is shape vs build material vs coating?

 

[flateric]

Neither the B-2 nor F-117 had pylons, so pylons seem unlikely for a stealth bomber.

Sure https://web.archive.org/web/20101223134504/https://up-ship.com/blog/?p=7121

 

[steelpillow]

I've never seen any indication that the B-21 would carry external ordnance. It seems absurd, in fact.

To be fair, the B-21 is designed with multi-role capability and not all of those roles will necessarily demand the same level of stealth. For example if it is hanging around and operating in a forward C3 role, there's not much point if your F-35s and drones can't hear what it wants them to do; the enemy will hear and geolocate the chatter even if they can't decode it or see the hardware on radar. So basic provision in the airframe to hang off maybe some pre-existing pod doing stuff, a short-range drone too wide to fit in the weapons bay, or even the odd drop tank, is not unthinkable.
But I agree that B-1 level stealth is no guide to even the B-2, never mind the B-21.

 

[Flyaway]

I've never seen any indication that the B-21 would carry external ordnance. It seems absurd, in fact.

To be fair, the B-21 is designed with multi-role capability and not all of those roles will necessarily demand the same level of stealth. For example if it is hanging around and operating in a forward C3 role, there's not much point if your F-35s and drones can't hear what it wants them to do; the enemy will hear and geolocate the chatter even if they can't decode it or see the hardware on radar. So basic provision in the airframe to hang off maybe some pre-existing pod doing stuff, a short-range drone too wide to fit in the weapons bay, or even the odd drop tank, is not unthinkable.
But I agree that B-1 level stealth is no guide to even the B-2, never mind the B-21.

I see the B-21 as being more like a stealthy F-111 which is something that means it should be able to fulfil multiple roles in the USAF, more so than the B-2. It would also make it more attractive to other countries. People inevitably compare it to the B-2 but I don’t think it is the successor, to that plane or should it be. Yes it can fulfil its tasks but it should be doing more than just that.

 

[overscan (PaulMM)]

How much of RCS is shape vs build material vs coating?

Shape most important, coating and build materials less. An untreated F-117 in metal would be much stealthier than an F-16 covered in F-117 RAM.

Advances in RAM/RAS for B-21 will build on the F-35 tech base with 'easy maintain' stealth as the goal.

 

[Forest Green]

Neither the B-2 nor F-117 had pylons, so pylons seem unlikely for a stealth bomber.

Sure https://web.archive.org/web/20101223134504/https://up-ship.com/blog/?p=7121

Okay, created but never used in anger AFAIK.

 

[Forest Green]

How much of RCS is shape vs build material vs coating?

Shape most important, coating and build materials less. An untreated F-117 in metal would be much stealthier than an F-16 covered in F-117 RAM.

Advances in RAM/RAS for B-21 will build on the F-35 tech base with 'easy maintain' stealth as the goal.

The paint is only part of the RAM, even before considering shape. Stealth is more than skin deep.

 

[steelpillow]

How much of RCS is shape vs build material vs coating?

Shape most important, coating and build materials less. An untreated F-117 in metal would be much stealthier than an F-16 covered in F-117 RAM.

Advances in RAM/RAS for B-21 will build on the F-35 tech base with 'easy maintain' stealth as the goal.

The balance does change over time.

The F-117 was the first generation, when flight-rated RAM was not very effective and so shape was the main driver. Also radars of the day were easily fooled by the "glitter" effect, so its slab-sided airframe proved the best option. It flies like a brick, but it has jet engines so WTF.

By the time of the second-generation B-2, RAM was a lot better, though still fragile. Detector engineers and operators were getting the hang of this glitter thing, and were also tracking the thermal signature of the exhaust. Range was more important. Digital FBW was finally advanced enough to fly an unstable tailless design. It all added up to both requiring and enabling better aerodynamics.

In this respect the B-21 is more of an incremental than a step-change, where improved stealth arises from better optimisation and refinement all round. It is in the less visible ways, such as materials, durability, cost and avionics, that the B-21 makes a quantum jump in capability.

Comparison between a standard F-117 and an F-16 given the B-21 coating/sealing materials would be an interesting one and I would not bet on it either way.

 

[Q-nimbus]

Some guys over at Dreamland Resort with a reputation of being well informed seem to think that the windows on the B21 are painted on. While I’m not convinced, they do have a few good points, and I’m curious what the experts here think of it.

 

[TomcatViP]

I think ppl are focused on something that does not need so much attention. The B-21 is the tip of the spear of an airforce that have flown stealth aircraft for 60 years (A-12 for example) and has one of its main stream fighter daily flown with synthetic visualization helmet (F-35). Their Raider is not a Business jet to fly around VIP. She does not need any windows unless for critical phase of flight and safety, which are:
- landing
- navigation

Landing:
The front windows are sufficient for that phase if we do consider that the pilot is seated way in front, close to the openings.
Navigation:
Without doubts, the USAF is planning for a total denial of GPS and wants its bomber to navigate accurately without external help. For a bomber that will fly at very high altitude, the easiest is to have side windows for the navigator that offer panoramic view outside (use terrain reference at great distance and stars). This is probably why the rear windows (the infamous angled ones) are that canted and narrow: when the plane sit noze high at extreme altitude, those are roughly horizontals and allow a rear seated navigator to see plainly outside, beyond the wings.

Obvious to me, this is a tandem seater. Either 1x1, 1x2 or a-la Prowler (2x2).

 

[Fluff]

With the brief to design a future proof aircraft, I keep thinking they may have as part of the main design, designed conformal fuel tanks/i.e. a large belly tank, might increase the RCS, but range limits detection, so your fuel for a long range combat trip, your on the belly fuel first, then drop the tank. For peacetime you have a very long ferry range - although you may want to keep that quiet.

I'm not convinced the navigator is looking out of the windows to navigate this aircraft. But in a real war with GPS compromised, some form of star tracker might be a good idea. But probably using a camera looking up. Obviously Inertial nav systems exist, but you are going to want an accurate fix if your launching guided weapons that cant use or get a GPS signal.

 

[BDF]

I'd be shocked if the windows are shaped for pilotage for navigation. If anything, the back system would be some sort of star tracker like the blackbird had. In any case, DARPA has or had a program for developing very accurate PNT in a GPS denied environment, to include weapons delivery. If that program has progressed to deployable systems its very likely that the Raider will have those system(s) installed. I also don't buy they window painted on rumor either.

 

[flateric]

I think ppl are focused on something that does not need so much attention. The B-21 is the tip of the spear of an airforce that have flown stealth aircraft for 60 years (A-12 for example) and has one of its main stream fighter daily flown with synthetic visualization helmet (F-35). Their Raider is not a Business jet to fly around VIP. She does not need any windows unless for critical phase of flight and safety, which are:

- landing
- navigation

Landing:
The front windows are sufficient for that phase if we do consider that the pilot is seated way in front, close to the openings.
Navigation:
Without doubts, the USAF is planning for a total denial of GPS and wants its bomber to navigate accurately without external help. For a bomber that will fly at very high altitude, the easiest is to have side windows for the navigator that offer panoramic view outside (use terrain reference at great distance and stars). This is probably why the rear windows (the infamous angled ones) are that canted and narrow: when the plane sit noze high at extreme altitude, those are roughly horizontals and allow a rear seated navigator to see plainly outside, beyond the wings.

Obvious to me, this is a tandem seater. Either 1x1, 1x2 or a-la Prowler (exe).

It's surely a tandem. 2x0.

 

[TomcatViP]

Mentioned already, but there is the fact that this angle give protection against ground based lasers (the windows tilts forward to keep a certain angle cte with the swept leading edge).

 

[Josh_TN]

I think ppl are focused on something that does not need so much attention. The B-21 is the tip of the spear of an airforce that have flown stealth aircraft for 60 years (A-12 for example) and has one of its main stream fighter daily flown with synthetic visualization helmet (F-35). Their Raider is not a Business jet to fly around VIP. She does not need any windows unless for critical phase of flight and safety, which are:
- landing
- navigation

Landing:
The front windows are sufficient for that phase if we do consider that the pilot is seated way in front, close to the openings.
Navigation:
Without doubts, the USAF is planning for a total denial of GPS and wants its bomber to navigate accurately without external help. For a bomber that will fly at very high altitude, the easiest is to have side windows for the navigator that offer panoramic view outside (use terrain reference at great distance and stars). This is probably why the rear windows (the infamous angled ones) are that canted and narrow: when the plane sit noze high at extreme altitude, those are roughly horizontals and allow a rear seated navigator to see plainly outside, beyond the wings.

Obvious to me, this is a tandem seater. Either 1x1, 1x2 or a-la Prowler (2x2).

I think the windows are present for taxing (particularly the side ones), landing and take off, and refueling. I can easily see the pilots in the program putting their foot down that they need an analog back up to any outside image rendering tech.

As for navigation, I'd be surprised if the B-21 didn't have a star tracker like the B-2, given the likely service ceiling of platform, along with a lot of other exotic PNT tech. As a nuclear delivery and ISR/processing node platform, exact location information would have to be secure and many times redundant.

 

[NeilChapman]

Landing:
The front windows are sufficient for that phase if we do consider that the pilot is seated way in front, close to the openings.
Navigation:
Without doubts, the USAF is planning for a total denial of GPS and wants its bomber to navigate accurately without external help. For a bomber that will fly at very high altitude, the easiest is to have side windows for the navigator that offer panoramic view outside (use terrain reference at great distance and stars). This is probably why the rear windows (the infamous angled ones) are that canted and narrow: when the plane sit noze high at extreme altitude, those are roughly horizontals and allow a rear seated navigator to see plainly outside, beyond the wings.

Obvious to me, this is a tandem seater. Either 1x1, 1x2 or a-la Prowler (2x2).

There is refueling.

But for the life of me they can auto-dock in space at 17,500 mph, and a Tesla can drive me to work. I don't see why automation is not tackled for this procedure. (Just not wBoeing)

 

[Q-nimbus]

I would be surprised if they used star based navigation on the B-21. An IRS these days is very accurate, especially if you can give it regular updates with GPS.

 

[Josh_TN]

I would be surprised if they used star based navigation on the B-21. An IRS these days is very accurate, especially if you can give it regular updates with GPS.

The USAF gets pretty old school about its nuclear weapons delivery. They didn't even use GPS in the B-61 mod 12, presumably as a security measure (and it still has a spin stabilized free fall option). I'd guess they still keep one around as a redundant navigational option, the same as B-2.

Let's Have Another Look At The B-2's Air Data Ports And Astroinertial Navigation System

The U.S. Air Force has just published some new close up shots of the B-2 during aerial refueling that show some of the bomber's characteristic nose

theaviationist.com

 

[Desertfox]

Re: External hardpoints, its likely the USAF is planning to replace the B-52 with more B-21s. For the B-52 mission of a strategic nuclear ALCM launcher stealth isn't a big deal (have you seen the RCS of a B-52!?). So losing some stealth in exchange for range (either internal or external fuel tanks) makes sense for the B-21, and even with external payloads the B-21 should still be much stealthier than a B-52.

 

[steelpillow]

Re: External hardpoints, its likely the USAF is planning to replace the B-52 with more B-21s. For the B-52 mission of a strategic nuclear ALCM launcher stealth isn't a big deal (have you seen the RCS of a B-52!?). So losing some stealth in exchange for range (either internal or external fuel tanks) makes sense for the B-21, and even with external payloads the B-21 should still be much stealthier than a B-52.

The re-engined/refurbished/revamped B-52 fleet is expected to complement the B-21 for several decades yet.
FWIW the RCS of the B-52 earned it the nickname in certain circles of "barn door", because that's what it looks like on radar. I don't know how much the revamp shrinks that by.

 

[paralay]

,

 

[flateric]

Some guys over at Dreamland Resort with a reputation of being well informed seem to think that the windows on the B21 are painted on. While I’m not convinced, they do have a few good points, and I’m curious what the experts here think of it.

Sure they are painted on

 

[flateric]

Wingspan 130 ft
Engines F135

Time to scale it up to 140 to fit the second bay, move both bays back and finally give pilots some place for toilet, lawn chair and microwave.
Engines are not F135 but something a-la PW9000 as it was known back in 2010
And there are no segmented LE with 'hairpins' even on B-2 mods for ages.

 

[Forest Green]

Wingspan 130 ft
Engines F135

Time to scale it up to 140 to fit the second bay, move both bays back and finally give pilots some place for toilet, lawn chair and microwave

I thought it had two bays but only rotary launchers for 6 cruise missiles?

 

[Hydroman]

I think they are transparencies, cockpit internally not finished, could have a dark film over the windows for the roll-out, B-2 was the same way in 1988. B-21 seems to be progressing just like B-2:

1. Six airframes in various stages of completion.
2. Roll-out of first vehicle.
3. Systems checkout, gear swings, engine runs, etc.
4. Low, medium, high speed taxi tests.
5. First flight.
6. Begin EAFB CTF flight test program.
7. (In parallel) Static/fatigue testing on non-flying structural vehicles (one for static, one for life cycle fatigue?)
8. Four vehicle flight test program (B-2 was six), probably to save cost, lots of simulation, lab and test bed testing reduces risk.

 

[fightingirish]

Aviation Week's Check 6 Podcast: Recapping B-21 Rollout, V-280 Contract Win
https://aviationweek.com/defense-space/podcast-recapping-b-21-rollout-v-280-contract-win

Media file: https://traffic.libsyn.com/secure/aviationweek/Recapping_B-21_Rollout_V-280_Contract_Win.mp3

 

[TomS]

Wingspan 130 ft
Engines F135

Time to scale it up to 140 to fit the second bay, move both bays back and finally give pilots some place for toilet, lawn chair and microwave

I thought it had two bays but only rotary launchers for 6 cruise missiles?

No one in the public knows. Paralay is just guessing on that wingspan, the idea of two 6-round rotary launchers is a guess, etc.

Seriously, we'll probably know more in a few months when some enterprising photog gets a decent pic of the underside after first flight. Until then, there are no facts, only speculation.

 

[NMaude]

Defence Updates has just put out a video about the features of the B-21A:

 

[flateric]

Do we really need these hamdrum videos citing wiki and speech transcrips with 10% of ads?

 

[La-Fuente Technologies]

Binkov's Video on the B-21

View: https://www.youtube.com/watch?v=5D_bOhsKCKE

 

[Flyaway]

I imagine by the way if anyone wonders what the so called RQ-180 looks like they just have to look at the B-21 I doubt it is much different just without the bit where you have to fit humans inside so to speak.

 

[flateric]

It's much different

 

[NMaude]

Do we really need these hamdrum videos citing wiki and speech transcrips with 10% of ads?

I don't think there's anything wrong with Defence Updates videos as I find to be short, informative and interesting.